Technical Field
The present disclosure relates to a light-emitting device, more particularly, to a light-emitting device with improved brightness.
Description of the Related Art
The light-emitting diodes (LEDs) have the characteristics of low power consumption and long lifetime, so the LEDs have been widely used in various appliances. Recently, since the LEDs have great progress in light efficiency, the LEDs have developed quickly and been used in lighting applications.
Normally, a conventional gallium nitride (GaN) based LED is grown on a sapphire substrate. In the process of electroding, especially forming n-electrodes, a part of a p-type semiconductor and an active layer have to be etched. Then, an n-electrode is formed on and connects to an n-type semiconductor. Such a LED structure may have a problem that the p-electrode and the n-electrode are not formed at the same level and do not have coplanar ends, so that it is a disadvantage to flip-chip mounting or surface mounting. Besides, the arrangements of the p-electrode and the n-electrode are inflexible so that it is unfavorable for various designs of the LED structure. More light-emitting area is etched away when forming the n-electrode. Thus, more light-emitting area is lost and thereby the light-emitting efficiency is degraded.
FIG. 1 shows a conventional LED device which is composed of a plurality of the LED units 28 with the structure described above electrically connected in an array. The plurality of the LED units 28 is formed on a substrate 100, and a plurality of electrical connecting layers 300 electrically connects the LED units 28. An insulator 140 is disposed under the electrical connecting layer 300 and between any two adjacent LED units 28. The start and the end LED units respectively comprise a second electrode 302 and a first electrode 301. The LED device has disadvantages as following: first one is the scheme of such electrical connection limits the electrode layout so it may be difficult to realize a complex electrical connection; second one is because of the difference in heights between the insulator 140 and the LED units 28, the electrical connecting layer 300 may crack easily and reliability of the LED device is degraded; last one is current spreading in each LED unit are not uniform.